Let's say the quantities are "a" and "b"
so... whatever "a" and "b" are, they add up to 9,500, thus
a + b = 9,500
now, "a" was invested at 12%, or 12/100
it yielded some amount, actually 12% of a, or 12/100 * a or 0.12a
the "b" amount was invested at 9%, or 9/100
it yielded 9% of b, or 9/100 * b or 0.09b
whatever 0.12a is, and 0.09b is, their sum or total yield was 1032
thus
0.12a + 0.09b = 1032
thus
solve for "a" to see how much was invested at 12%
what about "b"? well, b = 9500 - a
so... whatever "a" and "b" are, they add up to 9,500, thus
a + b = 9,500
now, "a" was invested at 12%, or 12/100
it yielded some amount, actually 12% of a, or 12/100 * a or 0.12a
the "b" amount was invested at 9%, or 9/100
it yielded 9% of b, or 9/100 * b or 0.09b
whatever 0.12a is, and 0.09b is, their sum or total yield was 1032
thus
0.12a + 0.09b = 1032
thus
solve for "a" to see how much was invested at 12%
what about "b"? well, b = 9500 - a