-----Original Message-----
I'm trying to complete an Excel 2000 model and I need
some help with the
basic algebra.

Can someone please rewrite this for me to solve for P1?

A = ( P1+ P2 ) / ( 1+ ( R1 * ( D1 + D2 ) ) (Eq.1)

Additionally, can this be rewritten to solve for P2?

A = P2 / ( 1 + ( R1 * D2 ) ) (Eq.2)


Yes; and Yes.


From Eq.1

A = P1 + P2
-------
1 + (R1 (D1 + D2))

so, as two responders have written,

P1 = A(1+R1(D1+D2)) - P2 (Eq.3)


From Eq.2

A= P2 / (1+ R1D1)

so, as you now know,

P2 = A(1+R1D2) (Eq.4)


However....

Substitute that value of P2 into Eq.3:

P1 = A(1+R1(D1+D2)) - A(1+R1D2)

Expand:

P1 = A + AR1D1 + AR1D2 - A - AR1D2

leaves

P1 = A.R1.D1

And Eq.4 expands to

P2 = A + A.R1.D2


Next question... what are the units ?

R1 (= 0.1/360) sounds like an angle in radians ?
i.e. a dimensionless ratio or pure number

So does P1 have the same units as A times D1 ?

Just checking....


RClay AT haswell DOT com