Question 507468
y-x=30


3x-x=30 ... plug in y = 3x (ie replace y with 3x)


2x=30


x=30/2


x=15


----

y = 3x


y = 3(15)


y = 45


So x = 15 and y = 45


=======================================================

# 2


2x + 2y =120 


2y + 2y =120 ... plug in x = y (ie replace x with y)


4y =120 


y =120/4


y =30


So x = 30 and y = 30