Easy!
You take the total number of students (55) then you remove the people that only like math and remove the people that only like English and remove the people that like none of them and what’s left is how many like both subjects.
55-15-18-5=17 students that like both subjects!
I hope this helps you
4,8 (x+4)=2,16
48 (x+4)=21,6
x+4=21,6/48
x+4= 0,45
x=0,45-4
x= -3,55
Depending on the way you look at the numbers, they are increasing/decreasing by 0.1.
0.36- 0.1 =0.26
0.26-0.1=0.16
0.16-0.1=0.06
0.06-0.1=-0.04
-0.04-0.1=-0.14
(Or vice versa by adding 0.1 starting with -0.14)
Make sense?