Question

(200+20*a):6=60, 320:(d*8-40=10

Answer 1

1. (200+20a):6=60
200+20a=60*6
200+20a=360
20a=360-200
20a=160
a=8

2. 320:(8d-40)=10
320:10=8d-40
32+40=8d
72=8d
d=9