The math problem that equals the same answer as 40+10 is 30+20.
Hope it works for you!
bearing in mind that an absolute value expression is in effect a piece-wise expression, because it has a ± version.
![\bf 3|x|+7=28\implies 3|x|=21\implies |x|=\cfrac{21}{3}\implies |x|=7\implies \begin{cases} +(x)=7\\ -(x)=7 \end{cases} \\\\[-0.35em] ~\dotfill\\\\ +(x)=7\implies \boxed{x=7}~\hfill -x=7\implies \boxed{x=-7}](https://tex.z-dn.net/?f=%20%5Cbf%203%7Cx%7C%2B7%3D28%5Cimplies%203%7Cx%7C%3D21%5Cimplies%20%7Cx%7C%3D%5Ccfrac%7B21%7D%7B3%7D%5Cimplies%20%7Cx%7C%3D7%5Cimplies%20%20%5Cbegin%7Bcases%7D%20%2B%28x%29%3D7%5C%5C%20-%28x%29%3D7%20%5Cend%7Bcases%7D%20%5C%5C%5C%5C%5B-0.35em%5D%20~%5Cdotfill%5C%5C%5C%5C%20%2B%28x%29%3D7%5Cimplies%20%5Cboxed%7Bx%3D7%7D~%5Chfill%20%20-x%3D7%5Cimplies%20%5Cboxed%7Bx%3D-7%7D%20)
4/9 x 27 = girls
12 girls
5/9 x 27 = boys
15boys
The best way to answer this would be making a graph
For 1 sign it costs 54.50 and he makes 15
For 2 signs it costs 59 and he makes 30
For 3 signs it costs 63.50 and he makes 45
For 4 signs it costs 68 and he makes 60
For 5 signs it costs 72.50 and he makes 75
This means that after 5 signs Larry will be making profit