Those are four equations for solving.
1) 4(p + 73) = 400
i) division property of equalities → p + 73 = 100
ii) subtraction propery of equalities → p = 27
Answer: p = 27
2) 15 = 9n/3
i) fraction simplification → 15 = 3n
ii) division property of inequalities → 5 = n
Answer: n = 5
3) r - 6/3 = 8
i) fraction simplification → r - 2 = 8
ii) addition property of equalities → r = 10
Answer: r = 10
4) 1 = n + 12/20
i) fraction simplification → 1 = n + 3/5
ii) subtraction property of equalities → 1 - 3/5 = n
ii) subtraction of fractions → 2/5 = n
Answer: n = 2/5