Question 514766
Let x, y and z be the lengths of the three sides (first, second, and third respectively)


x+y+z = 72


x+y+(1/2)x = 72


(y+10)+y+(1/2)(y+10) = 72


y+10+y+(1/2)y+5 = 72


(5/2)y+15=72


(5/2)y=72-15


(5/2)y=57


5y=57*2


5y=114


y=114/5


Now use this value of y to solve the equations

x = y+10

z = (1/2)x

to find the lengths of the other 2 sides