solving word problems with matrix

Question

the  sum of 1200usd is invested in three projects x,y,z at the ratio of 4:5:6 respectively.The expected cash inflow per annum is 700usd.The combined income for projects x and y is 140usd more than the income from project z.Calulate the amount invested in project z?

What is the cash inflow for project z:

What is the combined cash inflow for projects x and y?

Calculate the amount invested in project y?

Answer 1

4+5+6=15 so the amounts invested are 4/15*1200=$320 (x), 5/15*1200=$400 (y) and $480 (z).

Amount invested in z is $480.

x+y+z=700, so z+140+z=700, 2z=560, z=$280, cash inflow for z.

x+y+280=700, x+y=$420 or x+y=280+140=$420, combined inflow for x and y.

Amount invested in y is $400.