Ms. Hatcher teaches 20 third-graders and a number of fourth-graders that is twice the number of third-graders. Her co-teacher asked her to substitute for her fifth-grade class that has half as many students as the number of third-graders. How many students did Ms. Hatcher teach for the day? Think carefully first, then make a decision:
Ms. Hatcher taught 20 x 2 = 40 fourth graders for the day. She taught 20 / 2 = 10 fifth - graders as a substitute teacher for the day. Therefore, she taught 20 + 40 + 10 = 70 students for the day. So, the answer is 70.