I am in an introductory applied biostatistics class. We are doing an assignment related to power and sample size. We have been given mean values of blood pressures for two different groups along with standard deviations and we have to determine sample size needed per group to detect the above difference in blood pressures, provided power and level of significance.

Mean blood pressure for group 1 is 96.84 with a standard deviation of 5.63

mean blood pressure for group 2 is 105.99 with a standard deviation of 11.23.

level of significance is 0.01 and power is .80

we are using statistical software so I don't have to use formulas. However, I wanted to know what the difference is considered in this problem. Do I take the difference in the means of each group to be used as the determined difference in the calculation?