First solve for one variable 
(I chose bottom equation because it’s easier)
Get y alone:   Y = 5x
Now that we have y we can plug y into the top equation 
Plug in 5x for y:    2x + 5x = 7
Solve for x:  7x = 7 
X = 1
Now plug in the x value into the bottom equation to solve for y
Y = 5(1)
Y= 5
So, x = 1 and y = 5