Richard will increase the amount of time he studies each night from a period of 40 minutes to a period of 50 minutes by what percentage will Richard increase the amount of time he studies each night? A. 80%
B. 25%
C. 35%
D. 40%​

B. 25%

Step-by-step explanation:

40 divided by 25 is 10 and 10+40=50%

option 1 is correct.

step-by-step explanation:

y varies inversely with x and constant of variation is 4

the equation will be:

y = k/x

where k =4 so,

y = 4/x

if we put values of x of option 1 in the above equation and find values of y

y = 4/-2 => y =-2

y = 4/-1 => y = -4

y = 4/1 => y = 4

y = 4/2 => y =2

so, all the values of x and y are correct.

if we put values of x given in other options and find value of y we cannot find whole table satisfying the equation.

hence option 1 is correct.