Question 666131
Let's go through your steps:

Multiply (1) by 80. Good.

30x - 48y = 33

Multiply (2) by 35. Also good.

20x + 28y = 37 

Multiplying (1) by 2 and multiplying (2) by 3 will allow us to use elimination:

60x - 96y = 66
60x + 84y = 111

-180y = -45

y = 1/4

30x - 48(1/4) = 33

30x - 12 = 33

30x = 45

x =45/30 =  3/2

(3/2, 1/4)