The following model is generated as:

> y = 3*x1 + 3*x4 + rnorm(25,0,20)
> 
> plt(y,x1)
Error: could not find function "plt"
> plot(y,x1)
> plot(y,x3)
> y
 [1] 342.3260 276.7297 295.6997 232.8259 305.8473 278.8074 405.7824 155.9569
 [9] 345.5138 368.6950 332.5064 257.7586 158.6201 266.6928 334.7659 289.8067
[17] 316.9825 391.7623 304.4056 113.7588 363.7266 185.4743 215.7145 390.8597
[25] 210.1964
> y=round(y)
> 
> data = cbind(x1,x2,x3,x4,y)


 x1        x2         x3 x4   y
 68 93.900095  66.380051 58 342
 31 21.643177  -7.117950 58 277
 47 41.879896  47.634029 56 296
 45 54.683010  16.080304 38 233
 35 52.291663   5.757304 76 306
 30  8.333806  25.946259 53 279
 65 38.788196   3.064154 66 406
 28 23.092960  25.085900 33 156
 61 84.169109   8.633048 53 346
 78 91.313933  61.691069 36 369
 85 82.180256  24.903507 23 333
 58 50.833742  31.091365 33 258
 48 51.791208  21.201537  8 159
 57 22.310620 -19.525299 34 267
 67 43.251296  45.952124 46 335
 56 59.347753  18.174650 48 290
 55 69.892813  27.130214 42 317
 46 60.538443   7.064407 84 392
 56 62.706016  46.716775 54 304
 20  5.428405 -12.116529 10 114
 49 58.646290  57.174697 65 364
 43 20.847641  51.652028 23 185
 31 26.560393 -16.999710 43 216
 69 71.831524  72.489947 58 391
 49 58.997499   1.266059 21 210