Identify the expression as a numerical expression or a variable expression. for a variable expression, name the variable. 1 × 12
a. numerical expression
b. variable expression; a is the variable.
c. variable expression; there is no variable.
d. variable expression; l is the variable.

A. Numerical expression

The given mathematical expression only shows numbers which is primarily described by 1 and 12 which is in the operation of multiplication.

A variable expression could be that 2x+3=5
Where x is the variable in the given mathematical expression.

Okay so for every triangle has three angles that always add up to 180 degrees. and to tell the difference between whether they are secure, right or obtuse is that acute: has one angle that is less than 90 degrees. right triangle means there is at least one angle that is exactly 90 degrees. and an obtuse angle has an angle that is bigger than 180 degrees. i’ll do #13 as an example: 13. 40 and 50 so if every triangle has 180 degrees 40+50= 90 degrees then180-90= 90 degrees so the third angle is 90 degrees and because this triangle has a 90 degree angle it means it is a right triangle