can anyone help me wit this problem?

Question

six students in a small calss took an exam. the average of their grades was 75. the seventh student in the class was ill that day and took exam another day. when this student's score was included, the class average rose to 78. what was the seventh student's score?

Answer 1

96

When you calculate the new average you must divide by 7. He raised the average by 3; 3 X 7 = 21. So his score was 21 points higher than the previous average of 75.

Answer 2

75= x/6
X = 75*6= 450 (total all all 6 scores)

78 = x/7
X = 78*7= 546

546 - 450 = 96 was the seventh score