Solve the system of equations
-3y+4x=13
-5y-6x=-67

{x,y} = {67/16,-15/4}

Step-by-step explanation:

// Solve equation [2] for the variable  y

 [2]    2y = -8x + 26

 [2]    y = -4x + 13

// Plug this in for variable  y  in equation [1]

  [1]    4x + 5•(-4x+13) = -2

  [1]    -16x = -67

// Solve equation [1] for the variable  x

  [1]    16x = 67

  [1]    x = 67/16

// By now we know this much :

   x = 67/16

   y = -4x+13

// Use the  x  value to solve for  y

   y = -4(67/16)+13 = -15/4

a

step-by-step explanation:

hello,

b) 62.47% of the students are between 14 and 18 years old.

step-by-step explanation:

mean = 15 and standard deviation = 2

student between 14 to 18

formula used z-score

for age 14 , z score

using z-table , p(z> -0.5)=0.3085

for age 18 , z score

using z-table , p(z< 1.5)=0.9332

p(-0.5< z< 1.5)=0.9332-0.3085 = 0.6247

thus, 62.47% of the students are between 14 and 18 years old.

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step-by-step explanation: