Andy had 20% fewer marbles than Henry. When Andy gave 80 marbles to Henry, the numbers of marbles he had left was half of what Henry had. How many marbles did Andy have in the begining?

Question

Please help me

Answer 1

at start:
Henry ---- x marbles
Andy ---- .8x marbles

after give-away:
Henry --- x+80
Andy ---- .8x - 80

Andy's marbles = 1/2 of Henry's marbles

.8x-80 = (1/2)(x+80)
times 2
1.6x - 160 = x+80
.6x = 240
x = 400

So Henry had 400 and Andy had 320

check: after give-away
Andy is left with 240
Henry now has 480
Does Andy have half of what Henry has?? YES

Answer 2

at start:
Henry ---- x marbles
Andy ---- .8x marbles

after give-away:
Henry --- x+80
Andy ---- .8x - 80

Andy's marbles = 1/2 of Henry's marbles

.8x-80 = (1/2)(x+80)
times 2
1.6x - 160 = x+80
.6x = 240
x = 400

So Henry had 400 and Andy had 320

check: after give-away
Andy is left with 240
Henry now has 480
Does Andy have half of what Henry has?? YES

Answer 3

400for henry 320 for andy