A loud clap of thunder is measured at a noise level of 120 decibels (the unit for measuring sound). The next
two thunderclaps register a decrease of 20% followed
by a 25% increase in noise level. How loud, in decibels,
is the third thunderclap?

(0,-3) see attached graph

step-by-step explanation:

a. to solve the system, graph the two equations.

x = y+3 becomes y=x-3 has m=1/1 and b=-3. start at (0,-3) on the y-axis and plot a point. then move up 1 unit and 1 unit to the right. plot a point and connect.

y=-4x+3 has m =-4/1 and b=-3. start at (0,-3) on the y-axis and plot a point. then move down four units and to the right 1 unit. plot a point and connect.

the solution is the point (x,y) where the two lines intersect. by the graph below it is (0,-3).

b. to solve by substitution, substitute y = -4x-3 into x= y+3

x= (-4x-3) +3

x=-4x

5x=0

x=0

now substitute x = 0 back in to find y.

y= -4(0)-3

y=0-3

y=-3

solution is (0,-3)

c. use elimination by adding the equations together.

x-y=3

4x+y=-3

5x=0

x=0

then substitute into one equation to find y.

y=-4(0)-3

y=-3

make sure you have version 2.50

try looking in the very back of the book : )

step-by-step explanation:

you can download it here

i agree because i see the other persons thinking is clear

the transitive property of equality.

step-by-step explanation:

the correct answer is:

the transitive property of equality.

explanation:

we know that  ∠bcd is congruent to  ∠pbc. we also know that  ∠pbc is congruent to  ∠bad.

we can substitute  ∠bad for  ∠pbc in the first angle congruence statement to give us:

∠bcd is congruent to  ∠bad.

algebraically, the transitive property states if a=b and b=c, then a=c. it basically allows us to substitute equal values. since that is what we did, this is the transitive property.

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