Akind of glacier called a(n) forms when ice and snow build up in a mountain valley.

VALLEY GLACIER.

Step-by-step explanation:

Valley glaciers are brooks of running ice that are enclosed within steep walled valleys, often pursuing the direction of an old river valley. The downwards erosive operation of the ice creates the valley into a large U shape, in contradiction to the steeper V shape that is produced during the early stages of erosion by rivers. A U shape valley with a smooth ground is great proof of the past glaciation of a field.

you have to find the same variables -3n - 5n so this would be -3n +(-5n) which equals -9n

daren is correct because