It’s beautiful because if you set up the problem as proportion and you put 3/106 over to you would have to multiply by 2×3 to get a six and 1×2 to get it to so it’s 2 mph
Using the distributive property, you can distribute the 7 to y and -4. In other words, multiply the number outside of the parenthesis by each of the numbers in the parentheis. 7*y+7*-4 =7y-28
since the 5+2 is in parenthesis(don't know how to spell it its these things >( ) if you didn't know) you have to do 5+2 1st so thats 7 then you do 4*7 which is 28