Answer:
the sum of A, B, C and E = 23
Explanation:
single cone = $3
double cone = $5
total single = A = 3s
total double = B = 5d
As + Bd = 57
Cs + Ed = 15
A = 3 , B = 5
3s + 5d = 57
s + d = 15 (we don't know C and E yet)
multiply the second equation by 3 and substract it from the first equation
3s + 5d - 3s - 3d = 57 - 45
2d = 12
d = 6
Ed = 6
Cs = 15 - 6 = 9
A = 3 ($3)
B = 5 ($5)
C = 9 (single cones)
E = 6 (double cones)
Check:
(9 single cones × $3) + (6 double cones × $5) = 27 + 30 = 57
9 single cones + 6 double cones = 15
the sum of A, B, C and E:
A+B+C+E = 3+5+9+6 = 23
