Tommy is twice as old as his younger sister. the sum of the siblings' ages is 21. which equation can be used to determine the age of tommy's younger sister? a. x-2=21 b. x+2x=21 c. 2x=21 or d. x/2=21

Multiply −2x(6x^4−7x^2+x−5) express the answer in standard form. enter your answer in the box.

Select the correct answer from the drop-down menu. subtracting 3xy^2 from 8xy^2 gives the same result as the expression. [tex]3xy ^{2} - 8xy ^{2} [/tex][tex] { - 7xy}^{2} - {2xy}^{2} [/tex][tex] {7xy}^{2} - {2xy}^{2} [/tex]

Sundar used linear combination to solve the system of equations shown. he did so by multiplying the first equation by 5 and the second equation by another number to eliminate the y-terms. what number did sundar multiply the second equation by? 2x+9y=41 3x+5y=36