Axiom and postulates. They are considered to be self evident.
Coplanar lines are line witch lie on the same lie on the same plane. two parallel lines or two intersecting lines always lie in a plane. Thus, two line are coplanar, if and only if they are either parallel or intersecting. lines in three dimensional space are coplanar, only if they are not skewed lines.
When it says per month, it means to multiply. In this case, the expression would be;
25x+50
So however many months Fatima has spent at the gym, you would multiply that times 25 and add the initiation fee. Hope this helps.
By viewing equivalent ratios and rates as deriving from, and extending,
pairs of rows (or columns) in the multiplication table and by analyzing
simple drawings that indicate the relative size of quantities.