Answer
Larger investment yields 9.5%, smaller investment yields 7.5%
Work Step by Step
10,000 and 4,000 invested to make 1250 in income
10,000 invested at $x$ percent, 4,000 invested at $y$ percent
$x=.02+y$
$10000*x+4000*y=1250$
$x=.02+y$
$10000*x+4000*y=1250$
$10000*(.02+y)+4000*y=1250$
$200+10000y+4000y=1250$
$14000y+200=1250$
$14000y+200-200=1250-200$
$14000y=1050$
$14000y/14000=1050/14000$
$y=.075$
$x=.02+y$
$x=.02+.075$
$x=.095$
