It costs $107 for 10 students and $137 for 15 students. How much does it cost for 12 students?
1 answer:
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Answer:
-2c + 8d - 6
-6 + 5d - 2c + 3d
Step-by-step explanation:
When multiplying terms in a bracket, you need to multiply the term outside the bracket to all the terms in the bracket.
-(15-20d+15c) = (-
× 15) + (-
× -20d) + (-
× 15c)
Two minuses make a plus. One minus and one plus make a minus.
(- × 15) + (-
× -20d) + (-
× 15c) = (-6) + (8d) + (-2c)
Note that the terms can be presented in any order and still be correct.
(-6) + (8d) + (-2c) = -6 + 8d - 2c
Let us go through the options to see which ones are correct:
-2c + 8d - 6: Since all the terms are there, this option is correct!
-c + 40d - 8: Since none of the terms is there, this option is wrong.
-4c + 40d - 8: Since none of the terms is there, this option is wrong.
-3c + 8d - 3: Since (-3c) and (-3) are not the correct terms, this option is wrong.
-6 + 5d - 2c + 3d: If we evaluate the like terms (5d and 3d), the final answer would be -6 + 8d - 2c so this option is also correct!