Answer:
150
Explanation:
Originally, they had the same number, so they both had x marbles each.
David: x
Amrita: x
Amrita gives 50 marbles to David. Now they have:
David: x + 50
Amrita: x - 50
"he had 5 times as many marbles as her"
x + 50 = 5(x - 50)
x + 50 = 5x - 250
-4x = -300
x = 75
Each had 75 marbles to start with.
75 + 75 = 150
The total is 150.