Answer:
Jane had 20 stamps in the beginning
Explanation:
* Lets study the information in the problem
- Jane has unknown numbers of stamps
- She gave 10 of them to her friend
- Her mom give her twice as many stamps as she had in the beginning
* To solve the problem let the unknown numbers of stamps = x
∵ Jane had at the beginning x stamps
- She gave her friend 10 of them
∴ The rest with her = x - 10 stamps
- Her mom gave her twice as many stamps as she had in the beginning
∵ She had at the beginning x stamps
∴ Her mom gave her 2 × x = 2x
∴ The number of stamps with her now = x - 10 + 2x stamps
- She has now 50 stamps
∴ x - 10 + 2x = 50 ⇒ add the like term
∴ 3x - 10 = 50 ⇒ add 10 to both sides
∴ 3x = 60 ⇒ divide both sides by 3
∴ x = 20
∴ Jane had 20 stamps in the beginning