okay so for elimination you must eliminate either the x or the y variable then plug it back into an equation
2x+5y =20
+ -3x-10y = 37
-------------------------------
okay the easiest way would be multiplying the first equation by a 2 to cancel out the y's
(2x+5y =20) 2
+ -3x-10y = 37
-------------------------------
4x+10y =40
+ -3x-10y = 37
-------------------------------
the y's cancel out of the equation
4x =40
+ -3x = 37
-------------------------------
now add
x = 77
now plug the x value into either equation
2(77)+5y =20
154 + 5y = 20
5y = -134
y = -26.8
if you want to double check your answers plug back in your y and x values to check if the equation works
x = 77 and y = -26.8