Answer:
A(t)+900=x
B(t)+500=x
for the sake of things X represents the answer and as both need to equal the same it works out so that plugging it into a calculator should give you the answer
Explanation:
you could start by making a T chart on one Side A the other B starting with 900 at A and 500 at B go down by the appropriate increments 950, 600;1000, 700; 1050, 800; 1100, 900, 1150, 1000; 1200, 1100; 1250, 1200, and you guessed it, 1300, 1300. so there you go X=1300