2j+5=21
2j=16
j=8
<span>Jack is 8 years old.
</span>
Hope This Helped! :3
In these problems, it is always a good idea to find the total population. In this case, it would be the total number of people who went on the field trip.
28+18+4=50
There are 50 people total.
To find each fraction, just put the number of students/parents/teachers over 50 and simplify.
Students
28/50=14/25
Parents
18/50=9/25
Teachers
4/50=2/25
Hope this helps!
Answer: 65
Step-by-step explanation:
Since the mean mark of the 9 students is 50. Their total marks will be:
= 9 × 50
= 450
Since the marks obtained by 8 students are given, we add the marks together and this will be:
= 60+40+50+30+80+40+45+40
= 385
The score of the 9th student will be:
= 450 - 385
= 65
