Question 901119
x+y=780,
0.03*x+0.04*y=27.5
x=780-y
0.03*(780-y)+0.04*y=27.5
23.4-0.03y+0.04*y=27.5
0.01*y=4.1
y=410.0 at 4%
x=780-y
x=370.0 at 3%
check
0.03*370.0+0.04*410.0=27.5
11.1+16.4=27.5
27.5=27.5
ok