Answer:
The price of a doll=$7.5
Explanation:
Step 1: Express Dee's total cost
Dee's total cost can be expressed as;
Total cost=(price per doll×number of dolls bought)+(price per toy train×number of toy trains bought)
where;
Price per doll=d
number of dolls bought=6
Price per toy train=t
number of toy trains bought=2
Dee's total cost=$55
Replacing;
55=(6×d)+(2×t)
6d+2t=55...equation 1
Step 2: Express Joy's total cost
Joy's total cost can be expressed as;
Total cost=(price per doll×number of dolls bought)+(price per toy train×number of toy trains bought)
where;
Price per doll=d
number of dolls bought=4
Price per toy train=t
number of toy trains bought=7
Dee's total cost=$65
Replacing;
65=(4×d)+(7×t)
4d+7t=65...equation 2
Step: Solve simultaneously equation 1 and 2
4(6d+2t=55)>>>24d+8t=220
-
6(4d+7t=65)>>>24d+42t=390
(24d-24d)+(8t-42t)=220-390
-34t=-170
t=-170/-34
t=5
Replace the value of t in equation 1;
6d+2t=55, t=5
6d+(2×5)=55
6d+10=55
6d=55-10
6d=45
d=45/6
d=7.5
The price of a doll=$7.5