students are given 3 minutes for each multiple - choice question and 5 minutes for each free - response…

students are given 3 minutes for each multiple - choice question and 5 minutes for each free - response question on a test. there are 15 questions on the test, and students are given 51 minutes to take it. the system of equations shown can be used to find the number of multiple - choice questions, m, and the number of free - response questions, f, on the test. m + f = 15 3m + 5f = 51 how many multiple - choice questions are on the test? 3 5 12 14

students are given 3 minutes for each multiple - choice question and 5 minutes for each free - response question on a test. there are 15 questions on the test, and students are given 51 minutes to take it. the system of equations shown can be used to find the number of multiple - choice questions, m, and the number of free - response questions, f, on the test. m + f = 15 3m + 5f = 51 how many multiple - choice questions are on the test? 3 5 12 14

Answer

Explanation:

Step1: Despejar $f$ de la primera ecuación

$f = 15 - m$

Step2: Sustituir $f$ en la segunda ecuación

$3m+5(15 - m)=51$

Step3: Expandir la ecuación

$3m + 75-5m=51$

Step4: Combinar términos semejantes

$- 2m=51 - 75$ $-2m=-24$

Step5: Resolver para $m$

$m=\frac{-24}{-2}=12$

Answer:

C. 12