Question 900343
x+y=51,
10*x+20*y=750
x=51-y
10*(51-y)+20*y=750
510-10y+20*y=750
10*y=240
y=24
x=51-y
x=27 y=24
check
27+24=51
10*x+20*y=750
10*27+20*24=750
270+480=750
750=750
ok