His score increased by 21%
91-70=21 therefore he increased his score by 21%
she saved $3, and we know the discount is 15%, so her savings is that 15%, thus we know 15% of that purchase is 3.
let's say the full price is x, and therefore the 100%, if we know 3 is the 15%, what is x?

Cos 157.5º=-cos (180º-157.5º)=-cos 22.5=-cos(45/2)
cos Ф/2=⁺₋√((1+cosФ)/2).
In this case 157.5º is in the second quadrant, therefore we use the following equation:
cos Ф/2=-√((1+cosФ)/2). (we will have a negative number)
cos 157.5º=-cos (45/2)=-√((1+cos 45º)/2)
=-√((1+√2/2)/2)
=-√((2+√2)/4)
=-√(2+√2) / 2 (≈-0.92387...)
Answer: cos 157.5º= -√(2+√2) / 2
y=kx and y=
are two equations of constant of proportionality
Step-by-step explanation:
There are two equations for the constant of proportionality. That is
(i) Direct proportion
(ii) Inverse proportion
In direct proportion y=kx, Now
if x increases, then y also increases and if x decreases, then y also decreases. So, k is a constant proportionality.
In Inverse proportion y=
, Now
if x increases then y decreases and if x decreases, then y increases and k is a constant proportionality.
In direct proportion, we put y=1 and x=2, So k=
.
So, the equations y=kx and y=
are two equations of constant of proportionality.
Answer:
60
Step-by-step explanation: