Step-by-step explanation:
By substitution method,
-4p = 89/10 - 7q
p = (89/10 - 7q)/ -4
or, p = (89-70q)/10/-4
or, p = (89-70q)/-40
Again,
-12p + 35q = 477/10
or, -12(89-70q)/-40 + 35q = 477/10
or, 6(89-70q)/20 + 35q = 477/10
or, (534-420q)/20 + 35q= 477/10
or, (534-420q+700q)/20 = 477/10
or, (534+280q)/2 = 477
or, 534+280q = 954
or, 280q = 420
so, q = 3/2
