You're right until the fourth line up from the bottom. If (c-1) definitely has brackets round then 6=70(c-1) you need to multiply out to get 6=70c-70 then rearrange. You should get c=76/70 = 1.1 approx
a= 3
b= 2
d= 5
a=4b + (6/ c-1)- 15d
okey so il show how far i am. could someone please tell me where im goin wrong. many thanks
3= (8) + (6/ C-1) - 75
75+3 = 8+ (6/ C-1)
78 = 8 + (6/ C-1)
78-8 = (6/C-1)
70 = (6/C-1)
C-1 (70) = 6
C (70) = 7
C= (7/70)
C= 0.1