Adding and Subtracting Decimals

Evaluating One-Step Equations SPI 0706. 3.6 CCSS.Math.Content.7.EE.B.4a

Your friend’s mountain bike cost $245 more than his skateboard. His mountain bike cost $290. Use the equation x + 245 = 290 to determine how much did your friend’s skateboard cost?

1) Determine which inverse 2) Balance out the equation by operation is needed. doing inverse operations. THINGS TO REMEMBER: *You are trying to isolate the variable.

*You must use the inverse operation to solve equations!

Examples: Evaluate the following one-step equations. c a) x – 34 = -46 b) 290 = -245 + s c) -0.5r = -8 d) -1 =  6

q e) = -1.4 f) 62.5 + y = -77 g) q – 3.75 = 26.25 h) b – 7 = 36 2

t i) 33 = y – 44 j) 68 = k) 35d = 735 l) 84 = 7r 4

g m) -157 + q = 269 n) -9 = o) 72 = -8x p) b – 249 = 1  3 q) Solve the equation 16x = 208. a) x = 11 b) x = 12 c) x = 13 d) x = 14

r) Which problem situation best represents the equation 42 – x = 7? a) Craig is 42 years. His brother is 7 years older than he is. How old is Craig? b) Dylan has 42 days to finish his science project. How many weeks does he have left to finish his project? c) The total lunch bill for a group of 7 friends is $42. If the friends split the cost of the meal evenly, how much should each person pay? d) Each student in the Anderson Junior High Spanish Club has paid for a club t-shirt. If there are 42 students in the club and only 7 shirts are left to be picked up, how many students have already picked up their shirts?

Extra Practice:

Directions: Solve the following problems by doing the inverse operation and isolating the variable.

9 2 3 1) x = 27 2) 12 = x 3) ‒ x = 2 2 7 4

2 4) x = 100 5) 0.12x = 1 6) 0.8x = 19 5