Solve 30=R*[1+3.93.10^-3(0-20)]

$$30 = R \cdot [ 1 + 3.93 .10 ^ { - 3 } ( 0 - 20 ) ]$$

Solve for R

$$R=-\frac{30}{78599}\approx -0.000381684$$

Steps for Solving Linear Equation

Calculate 0.1 to the power of -3 and get 1000.

$$30=R\left(1+3.93\times 1000\left(0-20\right)\right)$$

Multiply 3.93 and 1000 to get 3930.

$$30=R\left(1+3930\left(0-20\right)\right)$$

Subtract 20 from 0 to get -20.

$$30=R\left(1+3930\left(-20\right)\right)$$

Multiply 3930 and -20 to get -78600.

$$30=R\left(1-78600\right)$$

Subtract 78600 from 1 to get -78599.

$$30=R\left(-78599\right)$$

Swap sides so that all variable terms are on the left hand side.

$$R\left(-78599\right)=30$$

Divide both sides by -78599.

$$R=\frac{30}{-78599}$$

Fraction \frac{30}{-78599} can be rewritten as -\frac{30}{78599} by extracting the negative sign.

$$R=-\frac{30}{78599}$$