Because LP and NP are the same measure, that means that MP is a bisector. It bisects side LN and it also bisects angle LMN. Where MP meets LN creates right angles. What we have then thus far is that angle LMP is congruent to angle NMP and that angle LPM is congruent to angle NPM and of course MP is congruent to itself by the reflexive property. Therefore, triangle LPM is congruent to triangle NMP and side LM is congruent to side NM by CPCTC. Side LM measures 11.
When substituting, you want to take the y value from one equation and plug it into the y variable in the other equation to find the x value. When you find the c value, you plug the number into one of the equations to get your y value.
It’s should be the second on so b and you should get it corrdct