Answer: 40 stamps
Step-by-step explanation:
Let Maddy = M and Simon = S
Given that maddy had twice as many stamps as simon. That is,
M = 2S ....(1)
After maddy sold 60 stamps, simon had twice as many stamps as maddy. That is,
S = 2( M - 60) .... (2)
Substitutes M for 2S from equation (1) into equation (2)
S = 2( 2S - 60 )
Open the bracket
S = 4S - 120
Collect the like terms
S - 4S = -120
- 3S = - 120
S = 120/3
S = 40
Substitute S into the equation (1)
M = 2 × 40 = 80
Maddy has 80 - 40 = 40 stamp
Therefore, Maddy has 40 more stamps than simon in the beginning.