The answer to the first one is 15.6 and the second one is 1.76
X = pencils, y = pens
8x + 6y = 8.50
4x + 4y = 5.....multiply by -2
----------------
8x + 6y = 8.50
-8x - 8y = -10 (result of multiplying by -2)
-----------------add
-2y = - 1.50
y = -1.50 / -2
y = 0.75 <=== pens cost 0.75
4x + 4y = 5
4x + 4(0.75) = 5
4x + 3 = 5
4x = 5 - 3
4x = 2
x = 2/4
x = 0.50 <== pencils cost 0.50
Answer:
A number is twice as much when put added by 4 to equal 12
2x+4=12
Step-by-step explanation:
If the perimeter is 98 cm, the sum of the lengths of two adjacent sides is 49 cm.
... (2x -1) + (3x +5) = 49 . . . . use the given information and relation
... 5x +4 = 49 . . . . . . . . . . . simplify
... 5x = 45 . . . . . . . . . . . . . . . subtract 4
... x = 9 . . . . . . . . . . . . . . . . . divide by 5
The left side dimension is then
... 2x -1 = 2·9 -1 = 17 . . . . cm
The top dimension is
... 3x +5 = 3·9 +5 = 32 . . . . cm
The rectangle is 17 cm by 32 cm.