If you are wanting to know how to solve these types of problems yourself, you need to know your decimal places!
For .875, the 8 is in the tenths place, the 7 is in the hundredths place, and the 5 is in the thousandths place.
You could read .875 as "point eight seven five" OR you...

The substitution method usually refers to a way to solve a system of equations. Do you have a second equation? If you do, the idea is to solve one equation for a variable, like y. So solve equation 1 for y. Then in equation 2, replace y with what it
equals in equation...

The key to this problem is using inverse operations to get m by itself. (If you don't recall, inverse operations "undo" each other. Like + and -, or x and /.)
A tip to remember: when solving for a variable in the denominator, like your m, it is always helpful to...

When you say "about equals," I have a feeling you actually mean "is congruent to."
This is an important concept in geometry: understanding the difference between being
equal and being congruent.
Equality only refers to numbers, not objects. For example, angles...