maths plse help me..
posted by Anonymous .
A man has Rs 50,000.He invests some part of it in one bank @ of 11 p.c.p.a. and the remaining money in another bank @ of 9 p.c.p.a.He gets a combined simple interest of Rs 5,400(i.e the S.I of one bank + S.I of another bank = 5,400).Then find the amount of money invested in both the banks individually

.11 a + .09 b = 5400
but
b = 50,000  a
so
.11 a + .09 (50,000 a) = 5400
.11 a + 4500  .09 a = 5400
.02 a = 900
a = 45,000
then
b = 5,000