Devaughn's age is three times sydney's age. the sum of their ages is 84 . what is sydney's age?

Explain how you can use the associative property to evaluate (7x50)x4.

To solve the system of equations below, pedro isolated the variable y in the first equation and then substituted it into the second equation. what was the resulting equation? { 5y=10x {x^2+y^2=36

Tom can paint the fence in 12 hours, but if he works together with a friend they can finish the job in 8 hours. how long would it take for his friend to paint this fence alone?