One Way:
We can change the mixed number to a decimal for comparing.

m =

m = 1.25 m
1.4 m > 1.25 m
Darren > Luke
Darren's jump was higher by (1.4-1.25)
0.15 m
Or another way change the decimal to a fraction and the mixed to an improper fraction too.

=

(Luke)
1.4 =

(Darren)
We need a common denominator to compare

(Luke)

(Darren)

(Luke)

(Darren)

Darren > Luke
By:

-

=

Which is also by
0.15 m
Darren jumps higher and by 0.15 m
Sarah would be incorrect, because the more numbers after the decimal, the smaller the number would be, because it is further away from the number one.
Answer:
a=3, c=-4, x=8
Step-by-step explanation:
5=4a-7
4a-7=5
4a=5+7
=12
a=12÷4
=3
3-8c=35
-8c=35-3
=32
c=-32÷8
=-4
-1/2x-7=-11
-1/2x=-11+7
=-4
x=4÷1/2
=4/1×2/1
=8
My work shown is how to get x. now that you have x plug it into the equation.
To test your answer add both 51 and 39, and you should get 90 (the measurement of a right angle)