Three is twenty-one, divided by the sum of a number and five

3=21/(x+5)
Cross multiply
3(x+5)=21
Divide 3
X+5 = 7
Subtract 5
X= 2

1. 0.3 •4 is the same as 4 groups of 0.32. 7•0.8 is the same as 7 groups of 0.83. it increases by 0.5 every time, so 0.5x4 it increases by 0.9 every time, so 0.9x5. 0.9•12=10.86. 0.47•5=2.35i can finish the next ones in a separate post

Neither is the answer