She made 4 two-point shots.
Explanation:
Let's call the number of two-point shots she score
t
and the number of free throws
f
.
Because we know she score 9 times we can write an equation:
t
+
f
=
9
if we solve for
f
we get:
t
+
f
−
t
=
9
−
t
f
=
9
−
t
We also know the total points score from these 9 shots was 13 and therefore we can write:
(
2
×
t
)
+
(
1
×
f
)
=
13
From the first equation we can substitute
9
−
t
for
f
in the second equation and then solve for
t
, the number of two-point shots.
(
2
×
t
)
+
(
1
×
(
9
−
t
)
)
=
13
2
t
+
9
−
t
=
13
t
+
9
=
13
t
+
9
−
9
=
13
−
9
t
=
4
