If $5a+2b=0$ and $a$ is two less than $b$, what is $7b$?
I need to find the value of $b$ first, and then multiply it by $7$ to get $7b$. Since $a$ is two less than $b$, I can write $a=b-2$ and substitute it into the first equation. This gives me $5(b-2)+2b=0$, which I can simplify by expanding and collecting like terms. I get $5b-10+2b=0$, or $7b=10$. Therefore, $b=10/7$, and $7b=7\cdot(10/7)=10$.

