I think that this an example of a paired t test. Since each student (subject) is given 2 treatments of the same material.
XZ=XY+YZ
JL=JK+KL
use the trigonometric values table or unit circle to calculate the expression
Answer: 23
When using multiplication with brackets, you multiply the number by all the numbers within the bracket before adding them together.
Therefore when it is 8(7 + 23) it basically means: 8(7) + 8(23)
