Multiply. (2.1 X 10/2) X (3.5 X 10/5)

we first solve each bracket

we can write 2.1 as 21/10 and 3.5 as 35/10

(21/10x10/2)x(35/10x10/5)

the 10's simplify

21/2x35/5=21/2x7=147/2=73.5

i leave the calculator work to you.

7. diameter 4 miles, circumference 4π miles

8. radius 0.2 miles, circumference 0.4π miles

[this is a bad problem because the actual radius of a car on the track is less than 0.2 miles so the answer is less than 0.4π miles]

9. radius 6 feet, circumference 12π feet

10. diameter 14 cm, circumference 14π cm

11. diameter 4.8 feet, circumference 4.8π feet

step-by-step explanation: