Step-by-step explanation:
13
[tex]3 + (20 \div 5) - ( {2}^{2}) [/tex]
[tex]3 + 4 - 4 = 3[/tex]
15
[tex] \frac{10 - {3}^{2} }{20 - (3 \times 4)} [/tex]
[tex] \frac{10 - 9}{20 - 12} [/tex]
[tex] \frac{1}{8} [/tex]
