A: [tex] \frac{5}{3} = \frac{N}{12} [/tex]
Multiply both sides by 12
Answer: [tex]N = 20[/tex]
B: [tex] \frac{7}{2} = \frac{42}{N} [/tex]
Multiply both sides by 2, [tex]7 = \frac{84}{N} [/tex]
Multiply both sides by N, [tex]7N = 84[/tex]
Divide both sides by 7,
Answer: [tex]N=12 [/tex]
C: [tex] \frac{N}{2}= \frac{50}{N} [/tex]
Multiply both sides by 2, [tex]N = \frac{100}{N} [/tex]
Multiply both sides by N, [tex] N^{2} = 100[/tex]
Simplify,
Answer: [tex]N = 10 , -10[/tex]
Hope I helped you!