\[\boxed{\mathbf{3.}\mathbf{162}\mathbf{.}\mathbf{ОК\ ГДЗ - домашка\ на\ }5}\]
\[\textbf{а)}\ 10 + 15 = 25 \cdot 3 = 75\ :15 =\]
\[= 5 \cdot 6 = 30 - 16 = 14\ :2 =\]
\[= 7 + 13 = 20 - 10 = 10\]
\[\textbf{б)}\ 90 - 45 = 45\ :15 = 3 \cdot 28 =\]
\[= 84 - 12 = 72\ :8 =\]
\[= 9 + 27 = 36\ :2 = 18 \cdot 5 = 90\]