A student’s grade is based on three tests: 30%, 30%, and 40%. If they scored 80 and 90 on the first two, what must they score on the third to get an overall 85?

Jawaban: 84.17

0.3×80 + 0.3×90 + 0.4x = 85 ⇒ 24+27+0.4x=85 ⇒ 51+0.4x=85 ⇒ 0.4x=34 ⇒ x=85. Wait, 0.4x=34 ⇒ x=85. So 85. But option 85 is there. So answerIndex should be 1 if options are as given. Actually, 85 is correct. So answerIndex 1. I'll adjust.