the diagram shows a triangle.\nwhat is the value of p?\np = \\square^\\circ

the diagram shows a triangle.\nwhat is the value of p?\np = \\square^\\circ
Answer
Explanation:
Step1: Sum angles to 180°
$$55 + (2p+12) + (10p-7) = 180$$
Step2: Simplify left side
$$55+12-7 + 2p+10p = 180$$ $$60 + 12p = 180$$
Step3: Isolate term with $p$
$$12p = 180 - 60$$ $$12p = 120$$
Step4: Solve for $p$
$$p = \frac{120}{12}$$
Answer:
$p = 10^\circ$