Uniform Series & Randomly Single Amounts $($cont$\text{'}$d$)$

Example $3\mathrm{.}4$

A design$-$build$-$operate engineering company in Texas that owns a sizable amount of land plans to $-$

mining and exploration company. The contract calls for the mining company to pay $$20,000$ per year for $20$ years beginning $3$ years from now $($i$.$e$.,$ beginning at the end of year $3$ and continuing through year $22)$ plus $$10,000$ six years from now and $$15,000$ sixteen years from now.