To solve this expression, which operation should be performed last? [21-(5 + 2)]^2 x 3

A. numbers inside brackets squared

B. subtract 7 from 21

C. multiply by 3

D. add 5 to 2

The average human heart beats 1.15 \cdot 10^51.15⋅10 5 1, point, 15, dot, 10, start superscript, 5, end superscript times per day. there are 3.65 \cdot 10^23.65⋅10 2 3, point, 65, dot, 10, start superscript, 2, end superscript days in one year. how many times does the heart beat in one year? write your answer in scientific notation, and round to one decimal place.

What are the solutions to the equation 4x2+3x=24-x

The ratio of the perimeters of two similar triangles is 4: 3. what are the areas of these triangles if the sum of their areas is 130cm2?