Afarmer grows only corn and lettuce. the farmer plans to plant 455 rows this year. the number of rows of corn will be 2.5 times the number of rows of lettuce. how many rows of each vegetable does the farmer plan to plant?

X - rows of corn,
y - rows of lettuce:
x = 2.5 y
x + y = 455

2.5 y + y = 455
3.5 y = 455
y = 455 : 3.5
y = 130
x = 2.5 * 130 = 325
The farmer plans to plant 325 rows of corn and 130 rows of lettuce.  

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