In science class, the ratio of boys to girls is 2:3. If there are 21 girls in the class, how many boys are there?

Can someone me my sister? she is in third grade. 50 points and brainlist! ones that are not answered. plz and thx!

Simplify a7/a4 a) 1/a3 b)-a/a2 c)a4/a3 d)a3

The level of co2 emissions, f(x), in metric tons, from the town of fairfax x years after they started recording is shown in the table below. x 2 4 6 8 10 f(x) 26,460 29,172.15 32,162.29 35,458.93 39,093.47 select the true statement.