Proszę o pomoc ! Pilne !
a)7a+3b+4c+5a-2b-8c
b)2a-4b-5c-6a-3b+2c
c)4a-2b+3-3a+6b-9
d)-4a+5b-7-2a-3b+3
e)3x+5y-4x+6y-7x-9y
f)-5x+2y-4x+5y+6x-3y
g)-2x+3y+3-2y-3x-4+y-4x+2
h)x-2y-4-2x-5+y-3+2x-6y
i)212x-323y-223y-5x+a-13
j) 4,5ab+212ba-527abc-312ba+37cab+acb- abd

Agroup of students want to create a garden. they do not know the exact measurements but they propose using a variable to represent the length and width of the garden. the length of the garden is 10 feet longer than double the width. use a single variable to write algebraic expressions for both the length and width of the garden. write an algebraic expression for the area of the garden. use mathematical terms to describe this expression.

Scores on the cognitive scale of the bayley-scales of infant and toddler development range from 1 to 19, with a standard deviation of 3. calculate the margin of error in estimating the true mean cognitive scale score, with 99% confidence, if there are 12 infants and toddlers in a sample.

Write an inequality for this description. - one fourth of the opposite of the difference of five and a number is less than twenty.