Earned $4200 and earned $174 in interest if one earns 3.5% and the other 4.5 % how much was invested at each rate

X + y = 4200 so x = 4200 - y

0.035x + 0.045y = 174

substitute x = 4200 - y into 0.035x + 0.045y = 174

0.035x + 0.045y = 174

0.035 (4200 - y) + 0.045y = 174

147 - 0.035y + 0.045y = 174

0.01y = 27

y = 2700

x + y = 4200

x = 4200 - 2700

x = 1500

answer

$1500 in 3.5%

$2700 in 4.5%