Divide by the number of items.
One centimeter equals 10 millimeters, therefore 90 times 10 equals to 900 millimeters. Your answer is 900 millimeters.
She could have hiked one 2 mile trail and one 1 mile trail or she could’ve hiked one 2.5 mile trail and another 0.5 mile trail
-2x + 3a - 6 - 5x - 7a....combine like terms
-7x - 4a - 6 <==