Go on, then, you work it out. Don't forget to divide each side by 5 and 10, respectively. If you manage it in under 5 minutes, congratulations - the rest of tonight's worksheet should only take you three hours.
Welcome to Year 10 Algebra. And if your kid's only 4 years old and you think you don't have to worry about this kind of bullshit yet, think again. Blink, and it will be upon you, so I strongly advise you to get practicing, toot sweet.

I was actually pretty good at maths in school. I studied both pure and applied all the way to VCE, without ever really understanding a thing. And that's when I had The Epiphany, declaring to anyone who would listen that I wanted to be (back of hand settles limply on forehead and eyes turn heavenward), an Actress, thereby shattering my mother's dreams of me becoming a doctor, forever.
(which was a good thing, really. I loathe hospitals).
And so ended the maths.
All this happened, like, 30 years ago. None of what I learned had any bearing on Real Life. The little maths ability remaining to me has been archived in the deepest recesses of my memory and can only be accessed by......um.....
Nothing, actually. A frontal lobotomy. It's pretty much all gone, folks.
That said, I have been bent over algebraic equations, night after night, for weeks with the Creative Genius, whose considerable visual talents, as impressive as they are, developed at the expense of and in inverse proportion to, her numeracy skills. Just say the word, 'maths', and my baby will turn pale and need to lie down for awhile.
Leaving not a lot to go on.
You see, as far as I can tell, they don't actually teach kids maths in school, they just give them worksheets.
To take home.
For you to muddle over after dinner. Then teach your kids how to do it. And you haven't even done the dishes yet.
Yay.
So, yeah.
Good luck with that.
ps. Thankfully, the actress thing wore off. After that, I did something much smarter.....I became a singer. Thirty years on, I have a CV that reads like a dog's breakfast, but I can carry a shitload of coffees from one side of a room to the other.