Question

Anna has more money than Betty. If Anna gave Betty $200, then they would have the same amount of money. While if Betty gave Anna $220, Anna would then have twice as much as Betty. Calculate the amount of money each girl has using the substitution method

Answer 1

Anna has $1460

Betty has $1060

Explanation:

let Anna's money be x

and Betty's money be y

If Anna gave Betty $200, then they would have the same amount of money

Anna's money will reduce by 200

x=x-200

Betty's money will increase by 200

y= y+200

if they have the same amount of money, the difference will be zero

x-200=y+200

x-200-y-200=0

x-y-400=0

x-y=400--------------1

this means that Anna has $400 more than Betty

if Betty gave Anna $220, Anna would then have twice as much as Betty.

Betty's money will reduce by 220

y=y-220

Anna's money will increase by 220

x=x+220

Anna's money will double that of Betty's

x+220=2(y-220)

x+220= 2y-440

x=2y-440-220

x=2y-660--------------------2

put x= 2y-660 in eqn 1

(2y-660)-y=400-------------------------1

2y-y=400+660

y= 1060

so Betty has $1060

put y= 1060 in eqn 1

x-y=400

x-1060=400

x=400+1060

x=1460

so Anna has $1460