Step-by-step explanation:

Answer:
1. no
2. 8
Step-by-step explanation:
1. 20 does not equal 4/5
2. 6x=48 divide 6 on both sides
x=8
Answer:
2.4
Step-by-step explanation:
Answer:
It is not valid since there is more than one variable being changed at one.
Step-by-step explanation:
Jackson changed the brand of soil, but he also changes the amount of water, and the amount of sunlight the plants are receiving, so his conclusion that the soil was more effective is not valid.
Answer:
x = 10 cm
Step-by-step explanation:
(3x + 2) + (3x + 2) + (4x - 5) + (4x - 5) = 134 cm
combine like terms:
14x - 6 = 134
add 6 to each side of the equation:
14x = 140
divide both sides by 14:
x = 10