algebra
posted by Briana on .
HELP! Please
Calvin invested $7500 for one year, part 12% annual interest and the rest at 10% annual interest. His total interest for the year was $890. How much money did he invest at 12%? Show work.

$X @ 12%.
$(7500X) @ 10%
I = 0.12X + 0.1(7500X) = $890.
0.12x + 750  0.1x = 890.
02x = 890  750 = 140
X = $7,000 @ 12%.