$$5 + 3\times 2 + 1$$ - 12

$$(5 + 3)\times 2 + 1$$ - 17

$$(5 + 3)\times (2 + 1)$$ - 16

$$5 + 3\times (2 + 1)$$ - 14

$${10-4\over 2} + 1$$ - 4

$$10-{4\over 2} + 1$$ - 9

$$10-4\over 2 + 1$$ - 2

$$10-{4\over 2 + 1}$$ - $$26\over 3$$

$$-{x\over 4}$$ - $$-{1\over 4} x$$

$$4x\over- 5$$ - $$-{4\over 5} x$$

$$-5x\over 4$$ - $$-{5\over 4} x$$

$$-x\over -4$$ - $${1\over 4} x$$

$$-10x\over -8x$$ - $$\frac{5}{4}$$

$$3b - 7$$ - a number multiplied by 3 then subtract 7

$$3(b - 7)$$ - a number subtract 7 then multiplied by 3

$$b - 7 \times 3$$ - a number subtract the product of 7 and 3

$$7 - 3b$$ - a number multiplied by 3 then subtracted from 7

$$3(7 - b)$$ - a number subtracted from 7 then multiplied by 3