Answer:
45
Step-by-step explanation:
Into 3 significant figures=4210
I believe it would be 0.75
If not that the only other thing I could think of would be 0.03, but it says he is already taking environmental science.
2a + 8b + 10
-3a + 7b + 16
2a + 8b + 10 - 5a -b +6= -3a + 7b +16
Next, group the similar figures
2a - 5a + 8b - b + 10 + 6= -3a + 7b + 16